http断点续传简单实现（java)

/* ]r8t^b
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**SiteFileFetch.java fl#gWAM  
*/ (Z;;v|F.i=  
package NetFox; kclClB:PS  
import java.io.*; W ZdEfY{  
import java.net.*; %5Hsd  
\ 'G%%%;4  
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public class SiteFileFetch extends Thread { ^x-vOGlR  
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SiteInfoBean siteInfoBean = null; //文件信息Bean PY- 1 oP  
long[] nStartPos; //开始位置 = _X#JP79  
long[] nEndPos; //结束位置 Q\|72NWS  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 2
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long nFileLength; //文件长度 (C>FM8$J  
boolean bFirst = true; //是否第一次取文件 4=!SG4~o  
boolean bStop = false; //停止标志 yr?*{;  
File tmpFile; //文件下载的临时信息 a+sHW<QeS  
DataOutputStream output; //输出到文件的输出流  AV{3f`  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） AlT41v~6
 
public SiteFileFetch(SiteInfoBean bean) throws IOException 2[6>h)  
{ ky>0  
siteInfoBean = bean; 3NAU|//J  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); _ZX"gHx  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); G|MjKe4}  
if(tmpFile.exists ()) ^K*uP^B=  
{ BB@I|)9O(  
bFirst = false; WJ":BK{NM  
read_nPos(); U+:oy:mz  
} QFt7L  
else 4gbi?UAmX  
{ VtIPw&KHW  
nStartPos = new long[bean.getNSplitter()]; erTb9`N4  
nEndPos = new long[bean.getNSplitter()]; f'P}]_3(  
} =2!AK[KxX  
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} Au3>=x`  
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public void run() t9T3e  
{ <{!^  
//获得文件长度 o8B_;4uB  
//分割文件 7xz~%xC.  
//实例FileSplitterFetch 9QE|
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//启动FileSplitterFetch线程 #vh1QV!Ho  
//等待子线程返回 #!V [(/  
try{ =5=D)x~  
if(bFirst) uis;S)+  
{ Pl^-]~  
nFileLength = getFileSize(); Y*nzOD$  
if(nFileLength == -1) 4bXAA9"  
{ tTrUVuZ
 
System.err.println("File Length is not known!"); bL*;6TzRK  
} SxV(.i'  
else if(nFileLength == -2) at7|r\`?-  
{ N'hj  
System.err.println("File is not access!"); {g9?Eio^F^  
} AdBF$nn[  
else kw)@[1U  
{ wXw pKm  
for(int i=0;i<nStartPos.length;i++) iC- ?F cA  
{ 5c6CH k`:  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); gNkx]bm  
} Y^5X>  
for(int i=0;i<nEndPos.length-1;i++) c*MSd  
{ "a;z  
nEndPos = nStartPos[i+1]; St/<\Y,wr  
} {6MLbL{
 
nEndPos[nEndPos.length-1] = nFileLength; /?X1>A:*  
} K|*Cka{  
} 9`{[J['V  
2}`Q9?  
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//启动子线程 jRIjFn|~{Y  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; . 2_t/2  
for(int i=0;i<nStartPos.length;i++)  /;LteBoY  
{ s'%KKC  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 47I5Y5  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), mtDRF'>P:  
nStartPos,nEndPos,i); e  iS~*@  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ?3 J  
fileSplitterFetch.start(); A6w/X`([O  
} ~:7AHK2  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 'G z>X :  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); %-"?  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", <}'hkEh{d=  
nEndPos = " + nFileLength); pKK&+umg  
// fileSplitterFetch[nPos.length-1].start(); 3$f%{
~3  
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7O5`&Z'-  
//等待子线程结束 $4.mRS97g  
//int count = 0; 4eb<SNi  
//是否结束while循环 :H[E W3Q  
boolean breakWhile = false; E:BEQ:(~L  
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4f,D3e%T|  
while(!bStop) ]e+IaZ[Wo  
{ v8g3]MVj3  
write_nPos(); pJ7wd~wF*  
Utility.sleep(500); -eAo3  
breakWhile = true; L^PZ\OC  
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for(int i=0;i<nStartPos.length;i++) t!^FWr&  
{ 3}O.B r|  
if(!fileSplitterFetch.bDownOver) g3{)AX[Uy  
{ e #l/jFJU  
breakWhile = false; Wo5G23:xz  
break; bu"Jb4_a>  
} cn ,zUG!-h  
} =DT
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if(breakWhile) gOw|s1`2,  
break; SxXh N  
}{/4sll  
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//count++; =0xuH>WY}w  
//if(count>4) Avw"[~
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// siteStop(); 9[5NnRv$P  
} Ne/jvWWN  
#f]R:Ix>  
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System.err.println("文件下载结束！"); e1{t qNJ  
} bj`cYL%  
catch(Exception e){e.printStackTrace ();} ]!H*oP8a*  
} , 6\i  
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o*/\oVOq  
//获得文件长度 l ,)l"6OV  
public long getFileSize() {B|U8j[  
{ g=; rM8W  
int nFileLength = -1; j-$aa;  
try{ l1`Zp9I  
URL url = new URL(siteInfoBean.getSSiteURL()); 6, ag\  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); "%ag^v9  
httpConnection.setRequestProperty("User-Agent","NetFox"); L.(T"`-i  
^8)&~q*  
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int responseCode=httpConnection.getResponseCode(); i2b\` 805  
if(responseCode>=400) ;nj'C1  
{ E=gD{1,?  
processErrorCode(responseCode); [$?S9)Xd  
return -2; //-2 represent access is error Kbx(^f12  
} x@.iDP@(  
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String sHeader; xTD6?X'4  
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f4
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for(int i=1;;i++) QHr 3J  
{ u]E%R&  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); @&+h3dV.V  
//Utility.log(in.readLine()); jLvI!q   
sHeader=httpConnection.getHeaderFieldKey(i); 7|zt'.56[  
if(sHeader!=null) P;KbS~ SlC  
{ [OG-ZcNu?  
if(sHeader.equals("Content-Length")) O|,+@qtH  
{ Fhn883  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ?>q=Nf^Q.  
break; A4';((OXy  
} V]H<:UE  
} 7x9YA$IE  
else &m8B%9w  
break; c%pW'UE&  
} CCq<y  
} K1O/>dN_\O  
catch(IOException e){e.printStackTrace ();} ml=1R>#'  
catch(Exception e){e.printStackTrace ();} <Q\`2{  
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Utility.log(nFileLength); !QVd'e  
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return nFileLength; i )3Y\u  
} 4)2*|w  
M
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//保存下载信息（文件指针位置） :;0?;dpO  
private void write_nPos() {KwLcSn  
{ o~P8=1t  
try{ c}Z,xop<P{  
output = new DataOutputStream(new FileOutputStream(tmpFile)); rA*,)I_v@  
output.writeInt(nStartPos.length); AG}' W  
for(int i=0;i<nStartPos.length;i++) Si]Z`_  
{ a^[io1}-  
// output.writeLong(nPos); \<lV),  
output.writeLong(fileSplitterFetch.nStartPos); @{I55EQ]  
output.writeLong(fileSplitterFetch.nEndPos); Q
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} $6!`  
output.close(); 3=bzIU  
} ' 1P_*  
catch(IOException e){e.printStackTrace ();} m OmT]X  
catch(Exception e){e.printStackTrace ();}
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} 'Iyk`=R  
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//读取保存的下载信息（文件指针位置） WtRy~5A2  
private void read_nPos() MW*}+ PC
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{ iXl1S[.l  
try{ DA@ { d-A  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); [&3"kb  
int nCount = input.readInt(); NlcWnSv  
nStartPos = new long[nCount]; ,7%(Jj$ ^  
nEndPos = new long[nCount]; 3}twWnQZJ  
for(int i=0;i<nStartPos.length;i++) 1}ZBj%z4l  
{ /4~RlXf@  
nStartPos = input.readLong(); pNiqb+^nz  
nEndPos = input.readLong(); 7KM!\"PM  
} _IlL'c5  
input.close(); =:"@YD^a4  
} >^InNJd  
catch(IOException e){e.printStackTrace ();} u]dpA  
catch(Exception e){e.printStackTrace ();} Ds}6{']K  
}  iI ^{OD  
(/*-M]>  
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private void processErrorCode(int nErrorCode) 3
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{ Q^39Wk@  
System.err.println("Error Code : " + nErrorCode); I
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} Jb tbW&EH  
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//停止文件下载 {Z?!*Ow  
public void siteStop() 7H>dv'  
{ R2J3R5S=[  
bStop = true; UVI=&y]c,p  
for(int i=0;i<nStartPos.length;i++) n,HWVo>([  
fileSplitterFetch.splitterStop(); ~{NDtB)  
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} _v$mGZpGY  
} W\KZFrV@  
//负责部分文件的抓取 @ics  
**FileSplitterFetch.java Sr+1.77}  
*/ =)I{KT:y  
package NetFox; O/-OW: 03  
@K+u+} R  
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import java.io.*; *v5y]E%aW  
import java.net.*; a9qZI  
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public class FileSplitterFetch extends Thread { pEaH^(I*  
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String sURL; //File URL ?b7vc^E&  
long nStartPos; //File Snippet Start Position gTQ6B,`/8  
long nEndPos; //File Snippet End Position X|q0m3jt  
int nThreadID; //Thread's ID zYs? w=  
boolean bDownOver = false; //Downing is over UNAuF8>K  
boolean bStop = false; //Stop identical ?t
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FileAccessI fileAccessI = null; //File Access interface ^|\?vA  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ?<}qx`+%Q  
{ H{$yy)@F  
this.sURL = sURL; 0WPxzmY  
this.nStartPos = nStart; 4OIN@n*4  
this.nEndPos = nEnd; ypifXO;m7  
nThreadID = id; iH$N HfH  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Uis P 8/k  
} dJ;;l7":~  
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public void run() $N ]P#g?Q  
{ W ][IHy<   
while(nStartPos < nEndPos && !bStop) 23fAc"@ B  
{ 9"aTF,'F/  
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pm  
a
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try{ w##Fpv<m  
URL url = new URL(sURL); (#,.;Y  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); v|'N|k l  
httpConnection.setRequestProperty("User-Agent","NetFox"); i'u;"ot=  
String sProperty = "bytes="+nStartPos+"-"; 7xcYM  
httpConnection.setRequestProperty("RANGE",sProperty); }9kq?  
Utility.log(sProperty); 97g-*K  
ejQCMG7  
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InputStream input = httpConnection.getInputStream(); *w6N&  
//logResponseHead(httpConnection); />oU}m"k  
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byte[] b = new byte[1024]; -Tt}M#W  
int nRead; Jzj~uz  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 2#[Y/p  
{ ~@O4>T+VW  
nStartPos += fileAccessI.write(b,0,nRead); !6%mt}h  
//if(nThreadID == 1) %In"Kh*  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); u`~{:V  
} GhT7:_r~  
`fRy"44nR  
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Utility.log("Thread " + nThreadID + " is over!"); !(~>-;A8  
bDownOver = true; aD^MoB3  
//nPos = fileAccessI.write (b,0,nRead); @88 efF  
} +Oscy-;  
catch(Exception e){e.printStackTrace ();} 2n=;"33%a  
} %q
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} n" ~*9'  
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//打印回应的头信息 -$q/7,os  
public void logResponseHead(HttpURLConnection con) |{nI.>  
{ tvUvd(8w  
for(int i=1;;i++)  R pbl)  
{ oGqv,[$qN  
String header=con.getHeaderFieldKey(i); d7P @_jO6  
if(header!=null) ba ?k:b  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); vB{b/xmah  
Utility.log(header+" : "+con.getHeaderField(header)); ?uN(" I  
else ..:V3]-D  
break; S#9SAX [  
} [:'n+D=T3M  
} C"{on%  
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public void splitterStop() $^!w`>0C  
{ cn0Fz"d  
bStop = true; "m3Y))a  
} iQF}x&a<  
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{;E/l(HNI  
} (?!0__NN;  
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/* GP$Y4*y/  
**FileAccess.java B,>FhX>h  
*//文件访问(定位，写) -Tx tX8v  
package NetFox; Mvv=)?:  
import java.io.*; u^9c`  
"Zk6B"o)  
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public class FileAccessI implements Serializable{ 
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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 3Y-v1.^j  
RandomAccessFile oSavedFile; H~i],WD  
long nPos; 81cmG`G7  
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public FileAccessI() throws IOException t] wM_]+  
{ m-RY{DO+  
this("",0); Ji[g@#  
} g-FZel   
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public FileAccessI(String sName,long nPos) throws IOException ~PnpYd<2  
{ EC'bgFe  
oSavedFile = new RandomAccessFile(sName,"rw"); 0Q>|s_  
this.nPos = nPos; E+zn\v  
oSavedFile.seek(nPos); 1,QZnF!.x  
} z-5#bOABW  
0)5Sx /5'  
17)M.(qmuP  
public synchronized int write(byte[] b,int nStart,int nLen) 5-HJ&Q
 
{ ,d>~='  
int n = -1; QtQ^"d65  
try{ =bWq 3aP)P  
oSavedFile.write(b,nStart,nLen); e0HP~&BRs  
n = nLen; %}XMhWn{  
} }dJ ~Iy  
catch(IOException e) 8 -;ZPhN&  
{ ~iZF~PQ1_  
e.printStackTrace (); HDyZzjgG  
} \STvBI?  
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return n; ~q(C j"7  
} xm5FQ) T  
0t?<6-3`/  
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} lO> 7`2x=F  
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' u};z:t  
/* sDm},=X}  
**SiteInfoBean.java y%bqeo L~  
*/ Os 2YZ<t  
package NetFox; \BaN5+
B6  
',`4 U F  
sFCs_u1tNN  
public class SiteInfoBean { j :Jdwf  
E)wT+\  
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private String sSiteURL; //Site's URL ;n{j,HB  
private String sFilePath; //Saved File's Path 5qQ(V)ah  
private String sFileName; //Saved File's Name l=~99m
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private int nSplitter; //Count of Splited Downloading File )^S^s>3  
b[o"Uq@8?  
50bP&dj&  
public SiteInfoBean() |uwteG5?$s  
{//nSplitter的缺省值为5 TL{pc=eBo  
//default value of nSplitter is 5 ku9FN  
this("","","",5); h;Ud
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} Rn(F#tI  
iH}rI'U.  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 'Oy5G7^R  
{ {R!TUQ5  
sSiteURL= sURL; 8tRhV2  
sFilePath = sPath; +Y9D!=_lj  
sFileName = sName; -_*XhD  
this.nSplitter = nSpiltter; _<F@(M5  
?Wz(f{Hm  
k=~pA iRDN  
} r]EZ)qp^@  
gc:p@<  
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public String getSSiteURL() oy2dA  
{ $4*E\G8  
return sSiteURL; \3(|c#c  
} OjlB0  

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k&_u\D"^"%  
public void setSSiteURL(String value)  !QW 0  
{ l)PFzIz=V  
sSiteURL = value; vua1iN1  
} aco}pXz  
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public String getSFilePath() m>-^K  
{ u3i|}`  
return sFilePath; "ko?att~  
} M|E2&ht  
19w,'}CGk  
&B7+>Ix,  
public void setSFilePath(String value) ?)o4 Kt'h  
{ t
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sFilePath = value; (zro7gKked  
} ?r'TH/>  
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public String getSFileName() ':2*+
 
{ U>B5LU9&  
return sFileName; k5%0wHpk=  
} MV;Y?%>  
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public void setSFileName(String value) Jn@Mbl  
{ cM<hG:4%wX  
sFileName = value; 0@e}hv;  
} {Fp`l\,  
s8yTK2v2\  
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public int getNSplitter() yc%E$g  
{ !%RJC,X  
return nSplitter; #9hXZr/8  
} x [{q&N!"`  
vu'!-K=0  
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public void setNSplitter(int nCount) XAULD]Q  
{ lF}$`6  
nSplitter = nCount; i h$@:^\  
} vPl6Dasr  
} WVT5VJ7*  
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/* vrm{Ql&  
**Utility.java =y-!k)t  
*/ ?Str*XA;  
package NetFox; Rqb{)L X*  
?4,*RCaI  
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public class Utility { :af;yu  
"U5Ln2X{J
 
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public Utility() 5Ckk5b  
{ mb~=Xyk&  
r@ T-Hi  
& L.PU@  
} RqN_vk\  
u5{5ts+:  
//线程睡眠 DtJTnvG~B  
public static void sleep(int nSecond) ++Ys9Y)*,  
{ kO,VayjT  
try{ wUIsi<Oj  
Thread.sleep(nSecond); S`2mtg  
} /,uSCITD  
catch(Exception e) Gkodk[VuLs  
{ gM
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e.printStackTrace (); Q&.IlVB[  
} iQm.]A  
}
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//日志 LE0J
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public static void log(String sMsg) sx-Hw4.a"  
{ I"F .%re  
System.err.println(sMsg); ><#2O  
} mS)|6=Y  
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public static void log(int sMsg) g@k#J"Q'[  
{ ,2 g M-  
System.err.println(sMsg); ]4 K1%ZV  
} .n)!ZN  
} _86*.3fQG  
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/* V'Z&>6Z  
**TestMethod.java 68J 9T^84  
*/ /XW&q)z-Hl  
package NetFox; 8=n9hLhqo  
iBtjd`V*  
 [`hE^chd  
public class TestMethod { {#w A!>.  
XYK1-m}2  
A'~%
_}  
public TestMethod() MR?*GI's  
{ ///xx/weblogic60b2_win.exe [B"dH-r7  
try{ C`yvBt40r  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); d Y:|Ef|v(  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); dK J@{d  
SiteFileFetch fileFetch = new SiteFileFetch(bean); t> x-1vf%  
fileFetch.start(); =$)4:  
} ~<2 IIR$H  
catch(Exception e){e.printStackTrace ();} hr_9;,EPh  
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y  
l}Q"Nb)  
} O:5Rp_?^  
j]!7BHC  
+&7[lsD*  
public static void main(String[] args) RVgPH<1X@e  
{ PkPDVv  
new TestMethod(); &*G5J7%w  
} w'oo-.k  
} z_:eM7]jv  
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