http断点续传简单实现（java)

/* z%cpV{Nu  
**SiteFileFetch.java X\dPQwasM  
*/ 7Ne`F(c  
package NetFox; 4?3*%_bDJ,  
import java.io.*; 2G9sKg,kL  
import java.net.*; ?h*Ngb
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public class SiteFileFetch extends Thread { O=Cz*j  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 1aQR9zg%  
long[] nStartPos; //开始位置 ![OKmy  
long[] nEndPos; //结束位置 cJ> #jl&  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ;[ag|YU$Y  
long nFileLength; //文件长度 #'<s/7;~  
boolean bFirst = true; //是否第一次取文件 $<[Q8V-  
boolean bStop = false; //停止标志 9]DMHA@  
File tmpFile; //文件下载的临时信息 L-}6}5[  
DataOutputStream output; //输出到文件的输出流 x\r[Zp|
  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） $aFCe}3b<  
public SiteFileFetch(SiteInfoBean bean) throws IOException >#Obhs|S{C  
{ \
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siteInfoBean = bean; +UGWTO\#ha  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); +U:U/c5Z^  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); NLz[F`I  
if(tmpFile.exists ()) E>}(r%B  
{ +oT/v3,  
bFirst = false; {"([p L  
read_nPos(); IJ`%Zh{f  
} G; *jL4  
else !((J-:=  
{ rh6gB]X]3:  
nStartPos = new long[bean.getNSplitter()]; jM'kY|<g;  
nEndPos = new long[bean.getNSplitter()]; &H`AS6  
} >)&]Ss5J  
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} 0E5
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public void run() qkEre  
{ !FqJP OGm  
//获得文件长度 b85r=tm   
//分割文件 zB?} {@  
//实例FileSplitterFetch p:GB"e9>H  
//启动FileSplitterFetch线程 LL}|#%4d  
//等待子线程返回 r}1.=a  
try{ j<HBzqP%6  
if(bFirst) oVK3=m@{  
{ S{qc1qj  
nFileLength = getFileSize(); E,/<;  
if(nFileLength == -1) tLz,t&h  
{ i Sm .E  
System.err.println("File Length is not known!"); 8)wxc1  
} FKX
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else if(nFileLength == -2) :?*|Dp1  
{ gyt[ZN_2  
System.err.println("File is not access!"); /5l"rni   
} GbLuXU  
else 1TagQ  
{ <yw6Om:n<  
for(int i=0;i<nStartPos.length;i++) xE2sb*  
{ 8K]5fkC|  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); =nQgS.D  
} "zn<\z$l  
for(int i=0;i<nEndPos.length-1;i++) * 7<{Xbsj^  
{ 0I`)<o-  
nEndPos = nStartPos[i+1]; su/!
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} .}wVM`81z  
nEndPos[nEndPos.length-1] = nFileLength; q,
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} 2+2Gl7" s  
} bI_6';hq!  
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//启动子线程 rW8.bMmM  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; *Va;ra(V2  
for(int i=0;i<nStartPos.length;i++) =Ts3O0"[  
{ Hz*5ZIw  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), .9cQq/{b  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), x?aNK$A~X  
nStartPos,nEndPos,i); ~6)A/]6  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Mx3MNX/  
fileSplitterFetch.start(); 7O=N78M  
} GV+K] KDI  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), -|
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); TQ/EH~Sz  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", m>H+noc^  
nEndPos = " + nFileLength);  ?)_?YLi  
// fileSplitterFetch[nPos.length-1].start(); fbG+
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//等待子线程结束 +PlA#DZu  
//int count = 0;  $:7
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//是否结束while循环 e;*GbXd|  
boolean breakWhile = false; ,v
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while(!bStop) 1&,d,<  
{ {CO]wqEj  
write_nPos(); -kGwbV}  
Utility.sleep(500); n0ZrgTVJ
 
breakWhile = true; H8'q Y  
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for(int i=0;i<nStartPos.length;i++) K~C6dy  
{ P1r)n{;  
if(!fileSplitterFetch.bDownOver) vky@L!&,  
{ u%o]r9xl'  
breakWhile = false; d;4LHQ0yU  
break; 3>~W_c9@  
} am'11a@*  
} TbUouoc  
if(breakWhile) xF#'+Y  
break; H n^)Xw  
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3  
//count++; &}:]uC  
//if(count>4) ;*H@E(g  
// siteStop(); KWq&<X5  
} ;ewqGDe'3  
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System.err.println("文件下载结束！"); M_OvIU(E  
} cbton<r~  
catch(Exception e){e.printStackTrace ();} D(' w<9.  
} i40'U?eG~6  
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//获得文件长度  1?oX"  
public long getFileSize() `X:o]t@  
{ } xy>uT  
int nFileLength = -1; FQ3{~05T  
try{ |[ )e5Xhd  
URL url = new URL(siteInfoBean.getSSiteURL()); b-`=
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); sa7F-X
M  
httpConnection.setRequestProperty("User-Agent","NetFox"); 2`[iTBZ=^  
c SV`?[a  
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int responseCode=httpConnection.getResponseCode(); Fx3CY W  
if(responseCode>=400) e#5LBSP  
{ _K4E6c_  
processErrorCode(responseCode); 7xhBdi[ dQ  
return -2; //-2 represent access is error yMd<<:Ap  
} o#^(mGj_.  
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String sHeader; 6XFLWN-)  
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for(int i=1;;i++) xa=Lu?t%<  
{ a7?)x])e  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); x @a3STKT  
//Utility.log(in.readLine()); J[k,S(Y  
sHeader=httpConnection.getHeaderFieldKey(i); G0izZWc  
if(sHeader!=null) PX} ~  
{ nB &[R  
if(sHeader.equals("Content-Length"))
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{ a(eKb2CX  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); vOIzfwYG9  
break; -
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} lB(E:{6OZ  
} <73dXTZ0  
else @mJ#~@*(  
break; e2dg{n$6"  
} f i_'Ny>#  
} r=J+  
catch(IOException e){e.printStackTrace ();} R/O>^s!Co  
catch(Exception e){e.printStackTrace ();} u alpm#GU  
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Utility.log(nFileLength); t/kMV6
 
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return nFileLength; z{q
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} >x3$Ld  
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//保存下载信息（文件指针位置） I&Z4?K  
private void write_nPos()
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{ -Gyj]v5y`c  
try{ Cd7imj  
output = new DataOutputStream(new FileOutputStream(tmpFile)); YjR`}rdwo  
output.writeInt(nStartPos.length); {tDH !sX  
for(int i=0;i<nStartPos.length;i++) \Qgc7ev  
{ M}S1Zz%Ii1  
// output.writeLong(nPos); om1@;u8u  
output.writeLong(fileSplitterFetch.nStartPos); %FhUjHm  
output.writeLong(fileSplitterFetch.nEndPos); WSKubn?7B  
} @CUYl*.PD  
output.close(); zgnZ72%  
} z|k0${iu#  
catch(IOException e){e.printStackTrace ();} qj#C8Tc7  
catch(Exception e){e.printStackTrace ();} z*w.A=r  
} _X6@.sM/2  
AhCqQ.O71  
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//读取保存的下载信息（文件指针位置） ^aONuG9  
private void read_nPos() }ZKG-~  
{ ? koIZ  
try{ k0(_0o  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); N+9W2n  
int nCount = input.readInt(); ?s-Z
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nStartPos = new long[nCount]; \+T U{vr  
nEndPos = new long[nCount]; _pN:p7l(  
for(int i=0;i<nStartPos.length;i++) n([9U0!gu  
{ )s~szmJoVD  
nStartPos = input.readLong(); /n3Qcht  
nEndPos = input.readLong(); E|K|AdL  
} A0l-H/
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input.close(); a`*Dq"9pV  
} Aw)I:d7F  
catch(IOException e){e.printStackTrace ();} '~\\:37+  
catch(Exception e){e.printStackTrace ();} &*YFK/]  
} ,vh$G 7D  
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private void processErrorCode(int nErrorCode) U(rY,4'  
{ 6g-Q  
System.err.println("Error Code : " + nErrorCode); (~ `?_  
} Jmml2?V-c  
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//停止文件下载 -FGM>~x  
public void siteStop() $l=&  
{ C)?tf[!_6  
bStop = true; g@2f&m  
for(int i=0;i<nStartPos.length;i++) M->
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fileSplitterFetch.splitterStop(); @9e}kiW  
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} !Pc&Sg  
} }`uFLBG3  
//负责部分文件的抓取 fWz=bJ"V  
**FileSplitterFetch.java eq6>C7.$  
*/ i1 >oRT{Z  
package NetFox; m|]:oT`M  
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import java.io.*; NyR,@n1  
import java.net.*; H{et2J<H  
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public class FileSplitterFetch extends Thread { + usB$=kJ  
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String sURL; //File URL P\ia ?9  
long nStartPos; //File Snippet Start Position ]RxJ^'a63  
long nEndPos; //File Snippet End Position ?ocBRla  
int nThreadID; //Thread's ID r]=Z :  
boolean bDownOver = false; //Downing is over =oT4!OUf  
boolean bStop = false; //Stop identical q
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FileAccessI fileAccessI = null; //File Access interface ^e{]WH
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException fl}!V4  
{ ZKTY1JW_  
this.sURL = sURL; 8.zYa(<2  
this.nStartPos = nStart; :ggXVwpe  
this.nEndPos = nEnd; .(%]RSBY  
nThreadID = id; |
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 y!VL`xV  
} PS3jCT  
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public void run() VVw5)O1'  
{ bk|?>yd  
while(nStartPos < nEndPos && !bStop) !<vy!pXg  
{ 0WSOA[R%[b  
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try{ iyv
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URL url = new URL(sURL); Jbn^G7vH<6  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); &Lbh?C  
httpConnection.setRequestProperty("User-Agent","NetFox"); #H]c/  
String sProperty = "bytes="+nStartPos+"-"; 8/<+p? 3p>  
httpConnection.setRequestProperty("RANGE",sProperty); `Jj q5:\&  
Utility.log(sProperty); i<{:J -U|  
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InputStream input = httpConnection.getInputStream(); ~wQ M ?h  
//logResponseHead(httpConnection); 'Ll'8 ps  
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byte[] b = new byte[1024]; :;jRAjq"  
int nRead; kjF4c6v  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) }t*:EgfI  
{ 3Mq%3jX  
nStartPos += fileAccessI.write(b,0,nRead); 'iU+mRLp  
//if(nThreadID == 1) -_M':  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^fj30gw7\5  
} A_Y5{6@  
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#sE:xIR  
Utility.log("Thread " + nThreadID + " is over!"); #y f  
bDownOver = true; Tm2+/qO,  
//nPos = fileAccessI.write (b,0,nRead); *z^Au7,&  
}  s&iu+>  
catch(Exception e){e.printStackTrace ();} SmUiH9qNd,  
} QYEGiT   
} ?-'GbOr!  
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//打印回应的头信息 n?QglN  
public void logResponseHead(HttpURLConnection con) $ I J^
 
{ deEc;IAo  
for(int i=1;;i++) b!qlucAeE  
{ 6OR)97  
String header=con.getHeaderFieldKey(i); akG|ic-~  
if(header!=null) n}C0gt-  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); i (`Q{l  
Utility.log(header+" : "+con.getHeaderField(header)); IEe;ygL#  
else 'vV+Wu#[  
break; JkQ\r$Y.  
} n5y0$S/D  
} y+ 4#Iy  
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public void splitterStop() >DAi
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{ ]GDjR'[z  
bStop = true; s@p:XO  
} {I/t3.R`  
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} U#%+FLX@w  
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/* LfJMSscfv  
**FileAccess.java S0ReT*I  
*//文件访问(定位，写) eH~T PH  
package NetFox; rP#&WSLVj  
import java.io.*; hcz!f  
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public class FileAccessI implements Serializable{ `~D{]'j  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 \}AJ)v*<  
RandomAccessFile oSavedFile; $wbIe
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long nPos; y,K> Wb9e  
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public FileAccessI() throws IOException /]of@  
{ ^a$L
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this("",0); 8tO.o\)h  
} !$#5E1:\  
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public FileAccessI(String sName,long nPos) throws IOException )$K\:w>  
{ v3(0Mu0J  
oSavedFile = new RandomAccessFile(sName,"rw"); ZiRCiQ/?  
this.nPos = nPos; k"6v& O  
oSavedFile.seek(nPos); |E;+j\  
} \YHl
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public synchronized int write(byte[] b,int nStart,int nLen) ""m/?TZq'  
{ 0<##8m@F8  
int n = -1; 'Er\68  
try{ wh!8\9{g  
oSavedFile.write(b,nStart,nLen); ZZ/k7(8  
n = nLen; cC]]H&'Hg+  
} i(*fv(z  
catch(IOException e) 9Q1w$t~Y  
{ N,.awA{  
e.printStackTrace (); EKS?3z%!  
} -J0OtrZ  
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return n; D&pp <  
} sXtt$HID=  
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} m}]QP\  
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/* #V
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**SiteInfoBean.java VV sE]7P ]  
*/ Lhr
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package NetFox;  t^}"8  
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public class SiteInfoBean { V;Q@'<w  
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private String sSiteURL; //Site's URL l<'}`  
private String sFilePath; //Saved File's Path foB&H;A4oC  
private String sFileName; //Saved File's Name m)]|mYjju  
private int nSplitter; //Count of Splited Downloading File )@] W=  
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public SiteInfoBean() :Zo^Uc:*w  
{//nSplitter的缺省值为5 eu?P6>urA  
//default value of nSplitter is 5 Y![8-L|Q  
this("","","",5); q^7=/d8  
} B*P;*re  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) GaV OMT  
{ .y0u"@iF  
sSiteURL= sURL; Yv2L0bUo:  
sFilePath = sPath; (cI@#x  
sFileName = sName; wM#l`I  
this.nSplitter = nSpiltter; 3>=G-AH/$K  
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} +;Gvp=hk  
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public String getSSiteURL() Hl*#iUq  
{ lTFo#p_(  
return sSiteURL; "{d[V(lE"  
} [4@@b"H  
\jS^+Xf?^  
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public void setSSiteURL(String value) s?fEorG  
{ +ZV?yR2yn  
sSiteURL = value; uC6e2py<[  
} 2z1r|?l  
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1F+nWc2b  
public String getSFilePath() ju4wU;Nu  
{ {UF|-VaG  
return sFilePath; RB;2  
} 75A60Uw  
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public void setSFilePath(String value) @V@<j)3P  
{ 6;Mv)|FJF  
sFilePath = value; 3E>]6  
} [|YJg]i-  
H>"P]Y)oX  
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public String getSFileName() 'b+ Tio  
{ `8TL*.9  
return sFileName; E~8J<gE  
} `_"?$ v2F  
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2d<`dQY{l3  
public void setSFileName(String value) Xob(4  
{ D2io3Lo$ov  
sFileName = value; 1KJ[&jS ]  
} G {a;s-OA3  
Yi19VU|/  
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public int getNSplitter() akwS;|SZ  
{ "IWL& cH3  
return nSplitter; w"A>mEex<  
} "c![s%  
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public void setNSplitter(int nCount) ;)sC{ "Jb  
{ 5 L-6@@/  
nSplitter = nCount; zCu+Oi6  
} eEeK ]8@  
} 6U]r3 Rr  
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/* tcI Z 2H%  
**Utility.java +Lo,*  
*/ uiWo<}t}{  
package NetFox; I#W J";kqB  
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public class Utility { T'N/A9{q  
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public Utility() ;3Q3!+%j  
{ P+0-h  
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} SWNT}{x]  
_G%kEt_4  
//线程睡眠 ZZ>(o d!B  
public static void sleep(int nSecond) u#3Cst8Y  
{ vQ{mEaH  
try{ )xTu|V  
Thread.sleep(nSecond); 5L\Im^  
} |lVi* 4za%  
catch(Exception e) vnX~OVz2  
{ 8=mx5Gwz-  
e.printStackTrace (); $- GwNG  
} [Fr <tKtB  
} >E>'9@Uh  
qi8~bQ{rH  
//日志  f^[m~  
public static void log(String sMsg) {65_k  
{ YO;@Tj2)x  
System.err.println(sMsg); Qr~yHFc1y  
} ^K^rl9  
A.<M*[{q  
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public static void log(int sMsg) z~;@Mo"*f  
{ Ul|htB<1:  
System.err.println(sMsg); K!gocNOf  
} t5S!j2E  
} KU_""T  
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#?bOAWAwLh  
/* 2*zMLI0.  
**TestMethod.java nB%[\LtZ
?  
*/ }]j#C  
package NetFox; IZxr;\dq6  
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public class TestMethod { ~8[`(/hj  
}`uq:y  
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public TestMethod() CbT ;#0  
{ ///xx/weblogic60b2_win.exe wd Di5-A4  
try{ 2c5)pIVEy  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); &lB>G[t  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); +)7h)uq  
SiteFileFetch fileFetch = new SiteFileFetch(bean); x|3G}[=  
fileFetch.start(); <ceJ!"L  
} t;lK=m|  
catch(Exception e){e.printStackTrace ();} 4n2*2 yTg  
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} ymA8`k5>@  
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public static void main(String[] args) p1,.f&(f  
{ z-`4DlJUS  
new TestMethod(); 8|rlP  
} /ASpAl[J  
} A*
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