http断点续传简单实现（java)

/* 1v,4[;{  
**SiteFileFetch.java V3F2
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*/ =\oNu&Q^  
package NetFox; KDHR}`  
import java.io.*; MZ% P(5  
import java.net.*; pMs%`j#T  
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public class SiteFileFetch extends Thread { 2+y4Gd 7  
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> `z^AB  
SiteInfoBean siteInfoBean = null; //文件信息Bean {Ivu"<`L3  
long[] nStartPos; //开始位置 Qv']*C[!z  
long[] nEndPos; //结束位置 !aII

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FileSplitterFetch[] fileSplitterFetch; //子线程对象 X0P<ifIv  
long nFileLength; //文件长度 OP``g/x)  
boolean bFirst = true; //是否第一次取文件 shP,-Vs#  
boolean bStop = false; //停止标志 ^Z\1z!{R  
File tmpFile; //文件下载的临时信息 =]etw  
DataOutputStream output; //输出到文件的输出流 U'Vz   
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） *3. ]  
public SiteFileFetch(SiteInfoBean bean) throws IOException L(AY)gB  
{ Nu|?s-  
siteInfoBean = bean; 8G(wYlxi  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); s}/YcU
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); UIhB  
if(tmpFile.exists ()) >/evL /  
{ hM+nA::w  
bFirst = false; x!LUhX '  
read_nPos(); u3ce\  
} >W 8!YOc  
else i[WTp??Uv  
{ BA L!6  
nStartPos = new long[bean.getNSplitter()]; S(/@.gI:f  
nEndPos = new long[bean.getNSplitter()]; YwHnDV
V+  
} d4A}BTs1  
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} #YhKAG@|  
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5  
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public void run() Gvj@?62  
{ Nb(se*Y#  
//获得文件长度 ;jI\MZ~l\  
//分割文件 C^l)
n!fq  
//实例FileSplitterFetch O`rrg~6#  
//启动FileSplitterFetch线程 4}#*M2wb  
//等待子线程返回 jZ.+b j >  
try{ A\k-OP]  
if(bFirst) +.[#C5  
{ Auv/w}zrr  
nFileLength = getFileSize(); ZhM-F0;`  
if(nFileLength == -1)
}RW4  
{ .r]n<  
System.err.println("File Length is not known!"); y 0M&Bh  
} aLhTaB-va  
else if(nFileLength == -2) ,cgC_%  
{ zgVplp  
System.err.println("File is not access!"); bNIT 1'v  
} `4l>%S8y:  
else E/AM<eN  
{ bCA3w%,kM  
for(int i=0;i<nStartPos.length;i++) SLZv`  
{ nef-xxXC^I  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); <}B|4($  
} lm-ubzJN  
for(int i=0;i<nEndPos.length-1;i++) IcaIB
)  
{ j:U>V7Kn3~  
nEndPos = nStartPos[i+1]; 2ZLK`^S  
} _v]I6<!5U  
nEndPos[nEndPos.length-1] = nFileLength; &tp5y}=n  
} Tz%l9aC  
} KGK8;Q,O  
/A##Yv!biR  
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//启动子线程 Ia>qVM0  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; HQ2in_'  
for(int i=0;i<nStartPos.length;i++) & }k=V4L  
{ w)DO"Z7  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), "D@
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), VO++(G)  
nStartPos,nEndPos,i); F~RUb&*/<  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); s?OGB}  
fileSplitterFetch.start(); RAf+%h*  
} `b9oH^}n j  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), I|iI ,l/9  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); LnR3C:NO k  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Fi*6ud\n!  
nEndPos = " + nFileLength); EEaKT`/d  
// fileSplitterFetch[nPos.length-1].start(); Q
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li NPXS+  
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//等待子线程结束 XXe7w3x
{  
//int count = 0; P+
"#xH  
//是否结束while循环 7"8HlOHA  
boolean breakWhile = false; /D)@y548~~  
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<-FZ-asem  
while(!bStop) E7*1QR{Q  
{ r("7 X2f  
write_nPos(); = ng\  
Utility.sleep(500); 'HOcK8}b  
breakWhile = true; nc$
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/0@}7+&  
<NS=<'U  
for(int i=0;i<nStartPos.length;i++) bh+R9~  
{ I0OsaX'  
if(!fileSplitterFetch.bDownOver) C-4I e  
{ : PQA9U|  
breakWhile = false; +{Q\B}3cj1  
break; _L# Tp  
} /a9+R)Al  
} <_42h|-  
if(breakWhile) ZO0_:T
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break; |mci-ZT  
sH+]lTSX6{  
~Bu~?ZJmd  
//count++; 0}P&G^%"  
//if(count>4) s'/.ea
V_  
// siteStop(); CR, Y%0vQ  
} }m0Lr:vq<r  
?%;uR#4  
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System.err.println("文件下载结束！"); ;B1}so1]  
} eZg31.  
catch(Exception e){e.printStackTrace ();} e@F&/c  
} u6B (f;  
,ew<T{PL  
CWC*bkd5a  
//获得文件长度 IP{Cj
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public long getFileSize() ^z)lEO  
{ &s] s]V)  
int nFileLength = -1; IXzad  
try{ #!,xjd  
URL url = new URL(siteInfoBean.getSSiteURL()); b*p,s9k7  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); aD3$z;E  
httpConnection.setRequestProperty("User-Agent","NetFox"); ;q$<]X_S)}  
7Y#b7H  
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int responseCode=httpConnection.getResponseCode(); a"WnBdFZ  
if(responseCode>=400) c/g(=F__[  
{ sPd5f2'  
processErrorCode(responseCode); ?*4]LuK6  
return -2; //-2 represent access is error 4J I;NN  
} x/9`2X`~  
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String sHeader; 2\s-4H| q  
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for(int i=1;;i++) Z?v9ub~%  
{ uO":\<1#  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); "BzRLg!J
 
//Utility.log(in.readLine()); wx57dm+  
sHeader=httpConnection.getHeaderFieldKey(i); E6@+w.VVO  
if(sHeader!=null) ]k,fEn(  
{ KDn`XCnk,  
if(sHeader.equals("Content-Length")) KNK0w5  
{ c)Y
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Xf#;GYO|2  
break; ~xHr/:  
} />$)o7U`+  
} 69IBG,N'  
else &"L3U  
break; 3$y]#
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} M8g=t[\  
} *, {b]6v  
catch(IOException e){e.printStackTrace ();} J@R+t6$3O  
catch(Exception e){e.printStackTrace ();} 1p{\jCi,2  
/}M@MbGMM  
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Utility.log(nFileLength); _ -?)-L&g  
2+Fq'!  
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return nFileLength; C6/,-?%)  
} h~nl  
)@Bt[mfrVD  
9VP|a-  
//保存下载信息（文件指针位置） {&2$1p/9'  
private void write_nPos() }}Q|O]e  
{ TuX#;!p6  
try{ =Qz8"rt#  
output = new DataOutputStream(new FileOutputStream(tmpFile)); pR~PB  
output.writeInt(nStartPos.length); /,B"H@J  
for(int i=0;i<nStartPos.length;i++) DVCc^5#  
{ a Y{E'K=  
// output.writeLong(nPos); .JH3,L"S^  
output.writeLong(fileSplitterFetch.nStartPos); T!/$@]%\7  
output.writeLong(fileSplitterFetch.nEndPos);  [bv.`  
} xXHz)w  
output.close(); 2o/AH \=2  
} O81})r*Y  
catch(IOException e){e.printStackTrace ();} -@i2]o  
catch(Exception e){e.printStackTrace ();} #xts*{u-#  
} c| p eRO.  
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//读取保存的下载信息（文件指针位置） r_R|.fl
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private void read_nPos() ,@[Q:fY  
{ ;((gmg7,  
try{ ;jnnCXp>  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); [#14
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int nCount = input.readInt(); /'">H-r  
nStartPos = new long[nCount]; GR|Vwxs<@P  
nEndPos = new long[nCount]; C\}m_`MR  
for(int i=0;i<nStartPos.length;i++) D0-C:gz  
{ i5-V$Qh  
nStartPos = input.readLong(); G19FSLrtA  
nEndPos = input.readLong(); YDDwvk H  
} U); ,Opr  
input.close(); bC)<AG@Z\  
} bz<wihZj  
catch(IOException e){e.printStackTrace ();} E!ZDqq
 
catch(Exception e){e.printStackTrace ();} kQ4%J,7e4  
} [*50Ng>P`  
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A #ZaXu/:X  
private void processErrorCode(int nErrorCode) N%>/ e'(  
{ [q_Yf!(m-  
System.err.println("Error Code : " + nErrorCode); ~LkReQI  
} ?VReKv1\  
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vwP
516EM  
//停止文件下载 EB>laZy>  
public void siteStop() 'jmcS0f -  
{ ( 6r9y3'  
bStop = true; BHU(
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for(int i=0;i<nStartPos.length;i++) a1om8!C  
fileSplitterFetch.splitterStop(); KWXJ[#E<W  
"
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b_
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} GK\'m@k  
} Npq=jlj  
//负责部分文件的抓取 |nocz]yU$  
**FileSplitterFetch.java s31^9a  
*/ y ?Q"-o (  
package NetFox; C'mmo&Pd  
,j2qY'wi  
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import java.io.*; <!=TxV>}A  
import java.net.*; Gb~q:&IUr  
93YD\R+q  
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public class FileSplitterFetch extends Thread { YM#XV*P0 q  
+n)(\k{
 
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String sURL; //File URL 8l)l9;4 6  
long nStartPos; //File Snippet Start Position a9D5qj  
long nEndPos; //File Snippet End Position $\a;?>WA"  
int nThreadID; //Thread's ID J-u,6c  
boolean bDownOver = false; //Downing is over q9Fc0(&Vf  
boolean bStop = false; //Stop identical Sw(%j1uL  
FileAccessI fileAccessI = null; //File Access interface ]`u{^f  

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f+/^1~^  
public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException `D#l(gZ  
{ 2|Tt3/Rn  
this.sURL = sURL; +ES.O]?>  
this.nStartPos = nStart; _NZ) n)  
this.nEndPos = nEnd; E$Ge# M@dM  
nThreadID = id; s?_b[B d  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ((X"D/F]  
} Ro%S_!  
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public void run() J-X5n 3I&  
{ vTB*J,6.  
while(nStartPos < nEndPos && !bStop) 2$3BluK  
{ pX*mX]  
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try{ KY_qK)H  
URL url = new URL(sURL); 9jvg[H  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Y
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httpConnection.setRequestProperty("User-Agent","NetFox"); >EMCG.**  
String sProperty = "bytes="+nStartPos+"-"; p
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httpConnection.setRequestProperty("RANGE",sProperty); j^64:3  
Utility.log(sProperty);  sRoZvp5  
}]?RngTt  
+)7NWR\  
InputStream input = httpConnection.getInputStream(); A4
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//logResponseHead(httpConnection); Y ,}p  
K1eoZ8=!  
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byte[] b = new byte[1024]; P-vA.7  
int nRead; Th!S?{v  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ]=_BK!O  
{ tv;3~Y0i  
nStartPos += fileAccessI.write(b,0,nRead); 4/d#)6  
//if(nThreadID == 1) s"Kp+tTWj  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); \SMH",u  
} =,?@p{g}  
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Utility.log("Thread " + nThreadID + " is over!"); )s^XVs.-  
bDownOver = true; '.^JN
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//nPos = fileAccessI.write (b,0,nRead); @-MrmF)<U  
} / Sp+MB9  
catch(Exception e){e.printStackTrace ();} O&X-)g=  
} 95(VY)_6#A  
} %%DK?{jo`  
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X0=R @_KY  
//打印回应的头信息 ")o.x7
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public void logResponseHead(HttpURLConnection con) OPjscc5  
{ |]B]0J#_  
for(int i=1;;i++) |%M%j'9  
{ 0\gE^=o[  
String header=con.getHeaderFieldKey(i); =
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if(header!=null) '7=*n_l  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ~MQN&  
Utility.log(header+" : "+con.getHeaderField(header)); ^\wosB3E  
else 9GQTe1[t4  
break; :
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} Dk7"#q@kx  
} B j*X_m  
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public void splitterStop() @{$SjR8Q $  
{ :)MZgW  
bStop = true; \tQi7yj4  
} {`}RYfZ
 
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} koie  
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/* ?c43cYb  
**FileAccess.java :r~?Z6gK  
*//文件访问(定位，写) Nls|R  
package NetFox; '<@PgO~  
import java.io.*; 4b<:67 %  
}y0UyOa{C  
<Z0Tz6/j,  
public class FileAccessI implements Serializable{ 8EP^M~rv  
]#J]f  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 2Hq!YsJ4]  
RandomAccessFile oSavedFile; B)c.`cfr*\  
long nPos; >uUbWKn3  
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public FileAccessI() throws IOException QP qa\87  
{ 9:esj{X  
this("",0); 6D
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} CE+\|5u W  
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public FileAccessI(String sName,long nPos) throws IOException ME7JU|@
Z  
{ 5ax/jd~}  
oSavedFile = new RandomAccessFile(sName,"rw"); S]9xqiJW  
this.nPos = nPos;  k&rl%P  
oSavedFile.seek(nPos); <2R=!n@b\  
} irL ehPX9  
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3)`}#`T  
public synchronized int write(byte[] b,int nStart,int nLen) 0ogTQ`2Z:  
{ B,A/ -B\  
int n = -1; :|d3BuY  
try{ /]vg_&)=  
oSavedFile.write(b,nStart,nLen); .]jKuTC\<  
n = nLen; K~Xt`  
} DsP+#PX  
catch(IOException e) "rX`h  
{ 38f9jF%7j  
e.printStackTrace (); s^E%Ukm  
} ~Ipl'cE  
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return n; Iw48+krm>  
} PvO>}(=  
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} 4sG^bZ,  
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8_:jPd!3  
/* z*
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**SiteInfoBean.java xKIm2% U9  
*/ ?}O\'Fa8
 
package NetFox; UW40Y3W0  
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public class SiteInfoBean { E5Z,4B  
aP2  
&a7KdGP8V  
private String sSiteURL; //Site's URL $Y>LUZ)b&8  
private String sFilePath; //Saved File's Path #N7@p}P  
private String sFileName; //Saved File's Name rrmr#a  
private int nSplitter; //Count of Splited Downloading File qy.Mi{=~:  
gzi~BJ  
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public SiteInfoBean() r"k\G\,%  
{//nSplitter的缺省值为5 A L

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//default value of nSplitter is 5 J
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this("","","",5); @VVBl I  
} \z0"  
# bP1rQ0
 
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Pij*?qmeQ  
{ TLw.rEN!;  
sSiteURL= sURL; CH!Lf,G  
sFilePath = sPath; 7H9&\ur9+  
sFileName = sName; ^jqQG+`?  
this.nSplitter = nSpiltter; -NHc~=m  
\za 0?b  
<mi*AY  
} \"|E8A6/  
W(Xb]t=19  
o[&*vc)  
public String getSSiteURL() wtIXZUx  
{ k0Rd:
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return sSiteURL; Xu2:yf4No*  
} [y&yy|*\  
Fzt{^%\`  
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public void setSSiteURL(String value) 'MVE5  
{ NirG99kyo  
sSiteURL = value; sWa`-gc  
} !.Eua3:V*  
$!H;,Jxv  
!EB<e5}8wK  
public String getSFilePath() X
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{ _H}8eU  
return sFilePath; GHaD32  
} WzDL(~m+Z  
 At3>  
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public void setSFilePath(String value) PFq1Zai}n|  
{ IT!u4iH[  
sFilePath = value; @Fvp~]jCb  
} 'I^3r~_  
Z8IY!d  
mmRxs1 0$  
public String getSFileName() vgKZr  
{ -Ri/I4Xj  
return sFileName; HQGn[7JW  
} 4AW-'W  
X\sOeb:]  
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public void setSFileName(String value) }w&W\g+E$  
{ C%&A9(jG  
sFileName = value; ?V&#nA  
} \USl9*E  
nM#/uuRl|  
2PZ#w(An&  
public int getNSplitter() -j& A;G  
{ [/
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return nSplitter; u]0{#wu;g  
} <UsFBF  
~xPU#m<  
`-Y8T\  
public void setNSplitter(int nCount) ?$$Xg3w_#  
{ }IJE%  
nSplitter = nCount; b,h@.s  
} qL2!\zt>g  
} vd
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T:/mk`>  
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/* qzk!'J3*r<  
**Utility.java |-l9Z  
*/ a=_:`S]}  
package NetFox; unvS`>)Np  
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public class Utility { (
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~~r7TP
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#IvHxSo&  
public Utility() /Z|K9
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{ S\M
+*:7  
X*w7q7\8-:  
U%rEW[j  
} %p;;aZG  
R :*1Y\o(  
//线程睡眠 ;UpdkY 1  
public static void sleep(int nSecond) FFtB#  
{ #
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try{ !&adO,jN+=  
Thread.sleep(nSecond); ()^tw5e'^  
} .k -!/^  
catch(Exception e) kD46Le++B  
{ z!G?T(SpA  
e.printStackTrace (); Vd;NT$S$  
} P
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}  5fq4[a  
X=@bzL;eq  
//日志 =d BK,/  
public static void log(String sMsg) ku)/ 8Z`$  
{ b5)1\ANq  
System.err.println(sMsg); 'YB{W8bR  
} BU<Qp$&  

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GYrUB59  
public static void log(int sMsg) s|][p|  
{ LFAefl\  
System.err.println(sMsg); {)I&&fSz  
} >r>pM(h  
} Mtaky=l8~I  
u p zBd]  
_"t"orD6  
/* p4uN+D`.U  
**TestMethod.java CG ,H  
*/ A;TNR  
package NetFox; " 1h~P,  
1()pKBHf  
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public class TestMethod { 4D[(X=FSU  
~zoZ{YqP  
Jq:Wt+a  
public TestMethod() Lh-+i  
{ ///xx/weblogic60b2_win.exe ikb;,Js  
try{ !jg< S>S5  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); .7HEI;4  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); '#
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SiteFileFetch fileFetch = new SiteFileFetch(bean); $\aJ.N6
rb  
fileFetch.start(); )&[ol9+\  
} * Na8w'Q  
catch(Exception e){e.printStackTrace ();} K8uqLSP '  
Ny$N5/b!!  
?]\v%[ho  
} l]L"Ex{  
8#|PJc  
g6H`uO  
public static void main(String[] args) ~PX#' Jr  
{ 7Q|v5@;pU  
new TestMethod(); /BrbP7  
} E8.1jCL>{"  
} /~+j[oB  
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